[personal profile] mjg59
Update: Patches to fix this have been posted

There's a story going round that Lenovo have signed an agreement with Microsoft that prevents installing free operating systems. This is sensationalist, untrue and distracts from a genuine problem.

The background is straightforward. Intel platforms allow the storage to be configured in two different ways - "standard" (normal AHCI on SATA systems, normal NVMe on NVMe systems) or "RAID". "RAID" mode is typically just changing the PCI IDs so that the normal drivers won't bind, ensuring that drivers that support the software RAID mode are used. Intel have not submitted any patches to Linux to support the "RAID" mode.

In this specific case, Lenovo's firmware defaults to "RAID" mode and doesn't allow you to change that. Since Linux has no support for the hardware when configured this way, you can't install Linux (distribution installers will boot, but won't find any storage device to install the OS to).

Why would Lenovo do this? I don't know for sure, but it's potentially related to something I've written about before - recent Intel hardware needs special setup for good power management. The storage driver that Microsoft ship doesn't do that setup. The Intel-provided driver does. "RAID" mode prevents the Microsoft driver from binding and forces the user to use the Intel driver, which means they get the correct power management configuration, battery life is better and the machine doesn't melt.

(Why not offer the option to disable it? A user who does would end up with a machine that doesn't boot, and if they managed to figure that out they'd have worse power management. That increases support costs. For a consumer device, why would you want to? The number of people buying these laptops to run anything other than Windows is miniscule)

Things are somewhat obfuscated due to a statement from a Lenovo rep:This system has a Signature Edition of Windows 10 Home installed. It is locked per our agreement with Microsoft. It's unclear what this is meant to mean. Microsoft could be insisting that Signature Edition systems ship in "RAID" mode in order to ensure that users get a good power management experience. Or it could be a misunderstanding regarding UEFI Secure Boot - Microsoft do require that Secure Boot be enabled on all Windows 10 systems, but (a) the user must be able to manage the key database and (b) there are several free operating systems that support UEFI Secure Boot and have appropriate signatures. Neither interpretation indicates that there's a deliberate attempt to prevent users from installing their choice of operating system.

The real problem here is that Intel do very little to ensure that free operating systems work well on their consumer hardware - we still have no information from Intel on how to configure systems to ensure good power management, we have no support for storage devices in "RAID" mode and we have no indication that this is going to get better in future. If Intel had provided that support, this issue would never have occurred. Rather than be angry at Lenovo, let's put pressure on Intel to provide support for their hardware.

Dell XPS 15 InfinityEdge

Date: 2016-09-21 10:29 pm (UTC)
From: [identity profile] xnox [launchpad.net]
I have skylake Dell XPS 15 Infinity Edge. It came with NVMe hard drive configured in a RAID setting which was not recognised by the Ubuntu installer. In the BIOS settings I was able to change that to something normal instead (it was listed as AHCI or some such), after that NVMe based installation worked with Ubuntu, but Windows 10 failed to boot. To resolve that, I had to reboot Windows 10 in safety mode, switch from raid to AHCI, boot into safety mode again, which I guess regenerated the "kernel modules included in the Windows boot process" or some such. After that, both Ubuntu and Windows 10 boot happily ever after. This is unfortunately well documented https://en.wikipedia.org/wiki/Advanced_Host_Controller_Interface#Boot_issues I wish windows would always include AHCI driver and/or the OEMs/Vendors did. Are we sure that it's not just the standard Intel Matrix Raid configuration which is supported by MDADM? Ubuntu Desktop installer doesn't support Intel Matrix RAID configuration out of the box at the time.

Re: Dell XPS 15 InfinityEdge

Date: 2016-09-23 02:14 pm (UTC)
From: (Anonymous)
Wouldn't that make the device slower? I haven't use the Ubuntu (or any other) installer for a while but maybe it runs an older kernel without the NVMe driver?


Matthew Garrett

About Matthew

Power management, mobile and firmware developer on Linux. Security developer at Google. Ex-biologist. @mjg59 on Twitter. Content here should not be interpreted as the opinion of my employer.

Expand Cut Tags

No cut tags